Paddock wired $100,000 to an account in his live-in girlfriend's home country, the Philippines, in the week before he unleashed the worst mass shooting in modern US history, according to multiple senior law enforcement officials.
The FBI met her at the airport and was taken out a back way to avoid the public eye.
Twenty-three guns were found in Paddock's suite and a search of a Mesquite, Nevada, home the couple lived in found 19 firearms, explosives and thousands of rounds of ammunition.
Fifty-nine people were killed after Paddock fired a semi-automatic gun on to a crowd of 22,000 people from his 32nd-floor hotel room at the Mandalay Bay Resort and Casino on Sunday night.
Paddock was found dead when police entered his hotel room.
Sheriff Joseph Lombardo told reporters that Danley is likely in the Philippines and remains a person of interest in the case.
Marilou Danley, 62, was met at Los Angeles International Airport by Federal Bureau of Investigation agents on Tuesday night after flying from Manila, multiple media outlets reported.
United States reports say that on top of his divorce proceedings, Stephen Paddock had a gambling problem.
Danley's neighbors said she described herself as a gambler. "We have discovered he was utilizing some of her identification".More news: MLB Wild-Card: Twins at Yankees Start Time, TV Schedule
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The Australian Associated Press reported that Danley was born in the Philippines and moved to Queensland in eastern Australia in the early 1980s.
The Las Vegas shooter's girlfriend has voluntarily returned to the United States from the Philippines as authorities probe for any possible links to the case.
Danley's sisters in Australia said in a TV interview there that they believe she couldn't have known about Paddock's murderous plans, and that he must have sent her away so she wouldn't interfere.
On Tuesday, authorities spoke with Marilou, who was in the Philippines.
Paddock, 64 at the time of Sunday's shooting, grew up to become a successful real estate investor who owned a number of apartments and houses, according to his brother Eric Paddock.
Investigators say that the shooting rampage was meticulously planned and included specially modified weapons.
Police are not aware whether the devices were transmitting - the FBI is investigating their use - but the Clark County sheriff told reporters he thinks the shooter might have used them to watch for people approaching his room.
But Paddock also had a habit of berating Danley in front of the coffee-chain's employees, according to Esperanza Mendoza.
'We are making progress, ' the sheriff said in determining Paddock's motive. Stanton said Lombard is expected to put out a statement later Wednesday. Investigators then wanted to know who he knew, and did they know about the attack.